C93 paddle mag release install question

So from my research the center of the hole for the paddle mag release should be 15.5mm/ .610" straight down from the center of the mag catch hole. I measured and scribed two lines that intersect to that point. However, when I install my clipped trigger group, the hole does not line up with my mark. The trigger pack hole is low and back from my measured center mark. So go with the measurements or the trigger pack location ? It's a Century C93 with a lower I clipped myself. Just checking, you know measure 1,000 times drill once, right. I'm a machinist by trade so I have the skills and tools just need to make sure I'm in the right spot. -Thanks